Early oil cooler not working but not leaking

[mskala]

2.2L engine re-assembled after larger pistons installed. All seemed okay
both before changing pistons, and now until a hotter day (~80F).
I found oil temp going to about 230F after 30+minutes on highway. It stays below
200F when outside it was ~55F. I checked that the thermostat was working (on
914 I could remove it while engine was still hot).

Can engine-mounted oil cooler have really poor efficiency if there were previous
top-engine oil leaks that got on the fins? Before re-assembly I could see through
the cooler, there is no blockage per-se. But I did have quite a bit of oil late last
year that turned out to be breather hose. Maybe being colder outside then I just
didn't notice any problem.

Thanks

[Flat6pac]

I would be looking for a dead mouse or a rodent nest on the cooler.
I run safety Kleen over the finning then blow air from bottom to top, then more safety Kleen.
You know the thermostat is working, change out the temp sensor.
Bruce

[mskala]

Well it's only been together for a few weeks, so I'm doubting mice at this
time. But yeah, I was thinking the easiest thing to do first is spray it a lot
and see what comes out. Then, I need to check, but I think it is possible
to remove without really pulling the motor.